diff --git a/MdePkg/Library/DxePcdLib/DxePcdLib.c b/MdePkg/Library/DxePcdLib/DxePcdLib.c
index b2e09af565..26e05edaf5 100644
--- a/MdePkg/Library/DxePcdLib/DxePcdLib.c
+++ b/MdePkg/Library/DxePcdLib/DxePcdLib.c
@@ -956,7 +956,8 @@ LibPcdGetNextTokenSpace (
   @param[in] Buffer             A pointer to the buffer to used to set the target variable.
 
   @return Return the pinter to the buffer been set.
-
+  @retval NULL   If SizeOfBuffer is set to MAX_ADDRESS, then SizeOfBuffer must be set 
+                 to MaximumDatumSize and NULL must be returned.
 **/
 VOID *
 EFIAPI